Over 2/3 (69%) of veterans from Operation Enduring Freedom (OEF) and Operation Iraqi Freedom (OIF) at Veterans' Administration (VA) medical centers screen positive for mental health problems. The most prevalent is post-traumatic stress disorder (PTSD). Substance use problems are also prevalent, particularly among veterans with PTSD symptoms. Despite their mental health needs, OEF/OIF veterans with PTSD are more likely to seek treatment for physical complaints than for mental health concerns. Although behavioral health care has been integrated into primary care in VA medical centers, veterans encounter significant barriers accessing this care. Although, psychosocial interventions such as cognitive-behavioral therapy (CBT) have been found to be efficacious for the treatment of problematic substance use and PTSD, providers in non- specialty care are unlikely to have the time or proper training to deliver this complex intervention. To address this public health concern, we propose to modify the content of an efficacious web-based CBT intervention for individuals with substance use disorders (Therapeutic Education System; TES), to target substance use, PTSD and other problems common among OEF/OIF veterans. The specific aims are: AIM 1. Develop an interactive, web-based psychosocial treatment for OEF/OIF veterans with hazardous or problematic substance use and PTSD symptoms. The planned intervention will be theoretically grounded in a CBT approach and will be delivered via an interactive system that employs informational technologies which are effective in promoting knowledge and skills. Development will be informed by expert collaborators, focus groups of OEF/OIF veterans, and feedback sessions in which experts and a 2nd group of veterans are asked to evaluate a beta-version of the program. AIM 2. Evaluate the efficacy of the web-based intervention with OEF/OIF veterans with hazardous or problematic substance use and PTSD symptoms. We plan to conduct a controlled trial in two primary care VA treatment centers. Participants will be randomized to: (1) Treatment as Usual (TAU) reflecting the model of treatment provided to most OEF/OIF veterans (n=81) or (2) TAU plus the web-based CBT intervention (n=81). Primary outcomes will be: a) number of heavy drinking days and/or number of days of illicit or non-prescribed drug use in the past 30 days; b) Quality of Life; and c) PTSD symptoms. AIM 3. Evaluate the cost and cost-effectiveness of the web-based intervention plus TAU relative to TAU alone. Cost-effectiveness ratios will be estimated to identify the incremental costs of the web-based intervention per increased quality adjusted life years (QALYs) and increased abstinence. Analysis will consider costs and cost effectiveness from a societal perspective, as well as from the VA system perspective to inform the adoption decision at a program level. Results of this study have the potential to markedly improve psychosocial treatment for substance use and related disorders among OEF/OIF veterans and enable rapid and widespread diffusion of a science-based intervention to this population. PUBLIC HEALTH RELEVANCE: Although a significant minority of veterans from Operation Enduring Freedom (OEF) and Operation Iraqi Freedom (OIF) in VA primary care centers present with co-occurring PTSD and substance use problems, most do not receive adequate treatment. To address this public health concern, we propose to modify the content of an efficacious web-based CBT intervention that will target substance use, PTSD and other problems common among OEF/OIF veterans, and will conduct an economic analysis that will compare costs & benefits of our web-based intervention with usual treatment at VA primary care settings. Results of this study have the potential to markedly improve psychosocial treatment for substance use and related disorders among OEF/OIF veterans and enable rapid and widespread diffusion of a science-based intervention to this population.